"We've got queries about where he was staying, how long he has been here and what his purpose was in being in the downtown area," Wieners said. "We believe he is a transient."

Any information about Cummins, who was shot on Tuesday, remains confidential because of the ongoing investigation, he said.

Wieners said the man threatened the officer. "The box cutter had the blade extended, and the officer was in fear of his life," he said.

Friendswood police confirmed that officers wear body cameras, although it was unclear whether the officer in the shooting was using one. The Houston Chronicle has made a public information request for any police videos of the incident.

Wieners declined to release the officer's name until he is notified that the Chronicle had requested his name. He said the officer's name would be released. "We want to be as transparent as possible," he said. "I think what you will find is that at the 72-hour mark we will have a comprehensive statement."

The officer has been placed on administrative leave pending the outcome of three independent investigations, Wieners said.

Police are conducting a criminal investigation into Cummins's actions; the police internal affairs division is determining whether the officer violated police policy, and the Galveston County District Attorney's Office is probing whether the officer violated the law.

The district attorney's office automatically investigates shooting deaths by officers and will present its findings to a grand jury, said James Haugh, who heads the district attorney's public integrity division. "Regardless of what the investigation reveals, this will go before a grand jury," Haugh said.

"It's really kind of subjective in terms of what the officer perceives and the reaction to it," Buckler said. "

An autopsy was completed on Cummins, police spokeswoman Lisa Price said, but the results were withheld by police.

The events leading to Cummins's death began when he walked into a convenience store at a Shell Service Station on the southeast corner of FM 2351 and South Friendswood Drive, said station owner Mehran "Ron" Jadidi.

Cummins asked Jadidi's employee if he could have a beer and pay for it the next day, Jadidi said. The employee refused.

Cummins was calm, never raised his voice or became belligerent, Jadidi said. "He said, 'I have to have a beer or I'll have to take it from you,' " Jadidi said.

The employee replied. "I'll have to call the cops," Jadidi said. Cummins replied, "You do what you have to do."

Cummins took a beer from the cool case and walked out of the store, Jadidi said. Jadidi called police about 3:10 p.m.

"He didn't look out of the ordinary," Beil said Wednesday. Cummins wasn't running and they saw nothing in his hands, he said.

Attorney Alton C. Todd was in his office on the southwest corner of South Friendship Drive and Willowick, about four blocks from the Shell station, when he heard three gunshots. Todd looked out the window and saw an officer with his gun drawn standing in the street.

Cummins had been shot near the front door of a corner building on the law office property.

Beil and Molina were about a half-block away when they heard the shots and ran to the scene, where they saw Cummins crumpled on the sidewalk and two officers with drawn pistols. "He wasn't moving," Beil said. "He was gone."

Wieners said police had interviewed about a dozen people and urged anyone with information to call 281-996-3300.